Fix Join Curves

[kwin]

The join curves button in the node tool is super important for making shapes out of multiple curves.  For instance if you want to make things semetrical.  However it doesnt work half the time.  It works fine when the endpoints arent touching, but if the endpoints are on top of eachother it should combine them into a single point with both handles.  I would say like half the time it works fine, but half the time you just end up with two points on top of eachother.  If you combine a lot of curves or break it into pieces and recombine you just end up with a bunch of unecesary points.  If you could make this work it would be so helpful.  I would even be cool with just having two buttons one for drawing a line between the endpoints and one for combining the endpoints.  Its just nearly imposible to do by hand and keep the exact same handles you had before.